Hello to all again!I am starting to get a feeling for the strength and options of the different op-families - but still have a "black hole feeling" concering customizing simple (or basic) geometries (under aspect of usabiltity and computing costs).

Two examples:- Creating a half sphere (Dome) with a circle as closing face- Creating a pyramid made of triangles only

What is the simplest und cheapest (CPU / GPU) way to do this exclusively in Touch?Is there a preferable way with pre-composing in another freeware and then import into Touch for further works like instancing etc?

In the topmenu of TouchDesigner, click Help->Operator Snippets and check some SOP examples out, in your case the Carve SOP and Cap SOP examples.

The Carve SOP can take the half of a Sphere SOP away which leaves you with a dome. The Cap SOP places a cap on the end of geometry, so this closes your dome with a circle.

If you use a Sphere SOP and set the rows&colums to 3, you get a double pyramid - use the carve SOP in the same way as above to make a single pyramid.

SOPs use only CPU power when cooked - so at least once when they are are built the first time, and further whenever you change them. You should try to do further transformations per frame in Geo COMPs (translate, rotate,scale) as that happens on the GPU and is extremely cheap, just like instancing also happens on the Geo COMP level on the GPU.

If you _have_ to do transformations each frame on the SOP level, do it in the end of the SOP chain, as otherwise all SOPs after your animated one have to cook each frame if their output is requested.